A room can feel chilly even when the heating is working hard. You may notice a cold spot beside the sofa, curtains that move when the window is closed, or a persistent feeling that the warmth disappears as soon as the thermostat turns down. Knowing how to spot window draughts helps you identify whether the issue is a minor adjustment or a sign that your windows are no longer doing their job properly.
Draughts are more than an inconvenience. They can make certain rooms uncomfortable, encourage you to turn up the heating and, over time, add to your energy bills. The good news is that most window draughts leave clear clues once you know where to look.
How to spot window draughts around the frame
Start on a cool or windy day, when air movement is easier to detect. With the window shut and locked, slowly move the back of your hand around the edge of the opening sash, particularly at the corners, along the hinges and near the handle. Your hand is sensitive to small changes in temperature, so you may feel a distinct cold flow where outside air is entering.
A thin piece of tissue can make this easier to see. Hold it close to the frame without touching the window. If it flickers or pulls towards a particular gap, there is likely to be air movement. Do this carefully and do not confuse a draught with air coming from a nearby trickle vent, extractor fan or open internal door.
Another simple check is to look at the curtains or blinds. Movement when the window is closed can suggest a draught, although lightweight curtains may also react to warm air rising from a radiator beneath the window. Switch the heating off briefly if you are unsure, then check again.
You should also inspect the outside of the window. Gaps between the window frame and brickwork, damaged sealant and cracked render around the opening can allow cold air and rain to reach the edges of the frame. A problem outside may be felt inside as a draught, even where the window itself appears to close normally.
Signs your window is not sealing properly
A well-fitted uPVC window should close firmly and create an even seal around its full perimeter. If it needs a hard push to shut, feels loose when locked or catches on one side, it may have dropped slightly out of alignment. This is common as windows age and can sometimes be corrected by a professional adjustment.
Look closely at the rubber gaskets that run around the sash and frame. They should be continuous, flexible and sit neatly in place. Gaskets that are flattened, split, brittle or missing in places cannot form a reliable weather seal. Dirt and paint residue can also stop them from sitting correctly, particularly on older windows that have not been cleaned around the seals.
A useful test is the paper test. Place a strip of ordinary paper between the frame and sash, then close and lock the window. If the paper slides out with very little resistance, the seal may be weak in that area. Repeat at several points around the window. One loose section may indicate a local adjustment is needed, while poor grip all around could point to worn seals or a more significant issue.
Do not assume every cold patch means a draught. Glass naturally feels colder than an insulated wall in winter, especially on older double glazing. A true draught involves moving air, whereas cold glass creates discomfort through heat loss. Both affect comfort and efficiency, but the solution may be different.
Check the parts people often miss
Draughts do not always come through the obvious gap between the sash and frame. The following areas are worth checking carefully:
- Handles and locking points: A worn handle, faulty lock or misaligned keeps can prevent the sash from pulling tightly against the seals when locked.
- Hinges: On casement windows, worn or damaged hinges can create a gap on the hinged side or at the top corner, even if the handle side appears closed.
- Glazing seals: The seals around the glass unit can shrink or deteriorate, allowing cold air at the edge of the pane.
- Frame-to-wall joints: Perished exterior sealant or gaps behind internal trim can allow air to bypass the frame.
- Trickle vents: These are designed to provide controlled background ventilation. They should not feel like a major cold blast when correctly used, but they are not meant to be permanently blocked.
If you have bay windows or a conservatory, inspect each section rather than assuming the whole area has one problem. A single poorly sealed opener or panel can make a large space feel much colder.
What condensation and noise can tell you
Condensation does not prove that a window is draughty, but it can help build the picture. Water droplets on the room-side glass usually mean warm, moisture-laden air is meeting a cold surface. This may be linked to inadequate ventilation, everyday activities such as cooking and drying clothes indoors, or inefficient glazing.
Mist or droplets between the panes of double glazing are different. They normally indicate that the sealed glass unit has failed. The insulating gas has escaped and moisture has entered the unit, reducing its performance. You may not feel an immediate draught, but the window will lose more heat and replacement of the glass unit may be required.
Outside noise can be another clue. If traffic, wind or neighbours sound unusually clear around a closed window, check the seals, lock and fit. Sound can travel through the same gaps as air. However, thinner or older glazing will also provide less acoustic insulation even when there is no visible gap.
Common causes of draughty windows
The cause often depends on the window’s age, design and installation. Older timber windows may have gaps caused by movement, worn putty or distorted sashes. Older uPVC windows can develop problems with hinges, locking mechanisms, gaskets and sealed units, while poor installation can leave gaps around any type of frame.
Sometimes the issue is simple maintenance. Leaves and debris in drainage channels can affect how the sash sits, while grime on seals can stop them seating evenly. Cleaning the frame, drainage slots and gaskets with warm soapy water can help. Avoid harsh solvents or abrasive cleaners, as they can damage uPVC and rubber seals.
It is tempting to apply foam tape or sealant straight away, but this can hide the underlying cause. Temporary draught-proofing may be useful for a minor gap, particularly in a rarely used room, yet it is not a long-term answer to failed hinges, poor locking or deteriorated frames. It can also interfere with opening windows, drainage and ventilation if applied carelessly.
When an adjustment or repair may be enough
If the window is structurally sound, the glass is clear and the frame has not warped or cracked, an adjustment may restore a better seal. A trained installer can check the hinges, locking points and compression of the gaskets, then make precise changes to improve how the sash closes.
Replacing worn gaskets, repairing hardware or changing a failed double-glazed unit can also be worthwhile in the right circumstances. This can be a sensible option where only one or two windows are affected and the rest of the property is performing well.
The trade-off is long-term value. If several windows are difficult to close, show internal condensation, have failed units or allow repeated draughts after repairs, replacement may be more cost-effective than continuing with piecemeal fixes. Modern A-rated uPVC windows are designed to provide improved thermal performance, reliable weather sealing, security and low maintenance.
When it is time to consider replacement windows
Consider a professional survey if you can feel air movement around several closed windows, the frames are damaged, locks no longer operate smoothly or the rooms remain cold despite regular heating. Replacement is also worth discussing if your windows are approaching the end of their serviceable life or you want to improve the appearance and security of your home at the same time.
The quality of installation matters as much as the window itself. Even an efficient new unit will not perform as it should if it is poorly fitted or the perimeter is not sealed correctly. Ask what will be checked during the survey, how the installation will be finished internally and externally, and what guarantee is provided.
At uPVC Houselift, we provide free, no-obligation surveys for homeowners who want clear advice on draughty or ageing windows. With more than 28 years of experience, our family-run team can explain whether adjustment, repair or replacement is the sensible route, with professional installation and a 10-year insurance-backed guarantee for complete reassurance.
A small draught can be easy to ignore during milder weather, but it rarely improves on its own. Checking your windows now can help you make a calm, informed decision before the colder months make a comfortable home harder and more expensive to maintain.
